Data with a strict QoS guarantee, such as voice, image, video and other multimedia service data, is a major concern for a mobile communication system. In order to enable a service to be used by a terminal user with an expected effect, for example, the images should be continuous when a user watches a Video online, the 3rd Generation Partnership Project (3GPP) clearly defines an end-to-end QoS structure in the mobile communication system and introduces multiple bearing and processing mechanisms, to guarantee that the mobile communication system can fully develop its technical advantages for providing various differentiated services for users.
QoS refers to the service quality provided by a system (server) for a user. QoS is for end to end, that is, the evaluation of QoS starts from a Source end and ends at a Target end. QoS parameters of bearer level include QoS Class Identifier (QCI), Allocation and Retention Priority (ARP), GBR, Maximum Bit Rate (MBR) and Aggregated Maximum Bit Rate (AMBR), wherein the QCI is a quantity level used for representing parameters of an access point transmitted and processed by a data packet for controlling the bearer level, and the main object of the ARP is to decide whether to accept or reject a bearer establishment or modification request in the case of limited resources. The parameter GBR represents a bit rate expected to be provided by a GBR bearer, when a transmission rate of a service is greater than or equal to the GBR, the QoS of the service is satisfied; when the transmission rate of the service is less than the GBR, the QoS of the service is not acceptable. The parameter MBR limits the bit rate which the GBR bearer can provide and represents an upper limit of the data rate expected to be provided by the GBR bearer.
The GBR bearer is mainly used for services such as voice, video, real-time game, and etc.; however, in order to guarantee the QoS of a service, it is needed to guarantee the QoS at access network side and the QoS at core network side. The QoS of the core network side service is guaranteed by a transmission priority, while the QoS of the access network side is guaranteed by allocating sufficient radio resources in a Base Station.
The QoS of the core network side service is easily implemented. However, for the QoS of a GBR service of the access network, the eNodeB decides the service priority of each user terminal through scheduling; therefore, the selection of a proper scheduling algorithm plays an important role on the obtaining of a GBR rate of a user terminal.
At present, there are three common scheduling algorithms at the base station side: Round Robin (RR) algorithm, Maximum Carrier to Interference (Max C/I) algorithm, and Proportional Fair (PF) algorithm.
The basic idea of the RR algorithm is to guarantee that user terminals in a cell occupy equal time of radio resources cyclically based on a determined order to perform communication. Although this algorithm provides fairest scheduling chances, it can not fully utilize the differentiation in the quality of user channels, both the system resource utilization ratio and the system throughput are very low. Besides, this algorithm does not consider the requirement of the user's GBR, thus the user's satisfaction degree is very low.
The basic idea of the Max C/I algorithm is to sort all prediction values of Channel Quality Indicator (CQI) of users and to schedule the users in a descending order. Although this algorithm can obtain a maximum system throughput rate, the service obtained by the user is not fair: a center user with good channel conditions would accept services all the time and the rate thereof would be greater than the GBR, while an edge user with poor channel conditions has a rate less than the GBR because of failing to obtain scheduling, thus the user's satisfaction degree is low.
The PF algorithm is that the eNodeB schedules one or more terminals having greatest Fair Factors (FF). The basic idea of the PF algorithm is to allocate corresponding priorities to users in a cell, wherein the user with the highest priority in the cell accepts services. The sector throughput rate and the service fairness of this algorithm are between the RR algorithm and the Max C/I algorithm.
                    FairFactor        i            ⁡              (        t        )              =                            TbSize          i                ⁡                  (          t          )                                                  Throughput            i                    ⁡                      (            t            )                          +        1              ,wherein FairFactori(t) represents a FF of UEi at moment t; TbSizei(t) represents a data amount UEi can transmit at moment t; Throughputi(t) represents the throughput of UEi in a time window with t as its end. For a User Equipment (UE) with good CQI, with its increase of the throughput, the priority would decrease to achieve fairness. This algorithm does not consider the requirement of the user's GBR either.
If a service in a communication system is of stream type, the service needs a GBR. If a service is a non-GBR service and the GBR is not configured for the user, then no service is provided for the user when the system lacks resources, which results in the user not satisfied. Therefore, a proper GBR is needed to be configured for a user both in a GBR service and a non-GBR service, so that the user can obtain a basic QoS. In this way, extensive operation policies can be provided.